冻结壁融化期间井壁受力变形分析与壁间注浆机理

Analysis of forced deformation of shaft lining and study of grouting mechanism during the melting of frozen wall

针对深厚冲积层冻结井筒早期壁间注浆封水效果不好的难题,通过实测数据分析和理论计算对深厚冲积层冻结井筒的冻结壁融化特性、井壁受力变形和壁间注浆机理进行了研究。通过对现场测温孔实测数据分析,得到了不同土层的融冻时间比;通过理论计算表明,在冻结壁完全融化后,外壁的外表面承受着水土压力、内表面作用有壁间水压,在此情况下,外壁内表面径向变形比单独冻结压力作用下的外壁变形要小的多,总体表现为向外反弹;而内壁在壁间水压作用下向内位移,由于内、外壁变形位移方向相反,壁间空隙形成,从而为注浆浆液扩散提供了通道。提出壁间注浆的最佳时机应在冻结壁完全融化、在压力水作用下壁间间隙已经形成、内壁还没有出水前。并给出了具体的壁间水压监测系统,实行了壁间注浆信息化。

In terms of a frozen shaft in deep alluvium,it used to be a difficult problem for the water sealing of early grouting of annulus between two shaft linings. This paper proposed a solution for the problem. Based on the analysis of in-situ monitoring data and theoretical calculation,the melting characteristics of frozen wall,the forced deformation properties of shaft lining and annulus grouting mechanism were studied in terms of frozen shaft in deep alluvium. Firstly,according to the analysis of measured data from thermometer hole,the time ratios between melting process and freezing process for different soil formations were deduced. Secondly,after frozen soil melted completely,the theoretical analysis showed that the soil and water pressure on outer surface and water pressure on inner surface for outside shaft lining had opposite effect,so the radial deformation for inner surface was much smaller than the displacement of shaft lining under frozen pressure before soil melting. Also the outer shaft lining would deform outward in radial direction.Otherwise,under the effect of water pressure,inner shaft lining would deform inward in radial direction. Therefore,annulus between two shaft linings would deform due to the opposite direction of radial displacement of outer and inner shaft. The annulus provided a passage for grouting and grout spreading. The paper suggests the optimal time for annulus grouting should take into account three factors,such as frozen wall melted completely,annulus forming completely under water pressure and no water coming out from inside shaft lining. An annulus water pressure monitoring system wasestablished,which can provide information for grouting process.